netdev - Re: [PATCH net-next v14] openvswitch: enable NSH support

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Message-ID: <20171101040435.GA66272@localhost.localdomain>
Date:   Wed, 1 Nov 2017 12:04:36 +0800
From:   "Yang, Yi" <yi.y.yang@...el.com>
To:     Eric Garver <e@...g.me>
Cc:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "dev@...nvswitch.org" <dev@...nvswitch.org>,
        "jbenc@...hat.com" <jbenc@...hat.com>,
        "pshelar@....org" <pshelar@....org>,
        "davem@...emloft.net" <davem@...emloft.net>
Subject: Re: [PATCH net-next v14] openvswitch: enable NSH support

On Wed, Nov 01, 2017 at 03:57:41AM +0800, Eric Garver wrote:
> On Mon, Oct 30, 2017 at 09:29:34AM +0800, Yi Yang wrote:
> [...]
> > +int nsh_pop(struct sk_buff *skb)
> > +{
> > +	struct nshhdr *nh;
> > +	size_t length;
> > +	__be16 inner_proto;
> > +
> > +	if (!pskb_may_pull(skb, NSH_BASE_HDR_LEN))
> > +		return -ENOMEM;
> > +	nh = (struct nshhdr *)(skb->data);
> > +	length = nsh_hdr_len(nh);
> > +	if (!pskb_may_pull(skb, length))
> > +		return -ENOMEM;
> > +
> > +	nh = (struct nshhdr *)(skb->data);
> > +	inner_proto = tun_p_to_eth_p(nh->np);
> 
> If you fetch inner_proto before the second pskb_may_pull then there is
> no need to reload the nh pointer as you won't use it later.
> 
> > +	if (!inner_proto)
> > +		return -EAFNOSUPPORT;
> > +
> > +	length = nsh_hdr_len(nh);
> 
> You already have the length from above. No need to get it again.

Good catch, fixed in v15.